Dental oven



'Patched Apr; 21, 1925."

` UNIT-En A,s1-Aras PATIENT oFFicE.

j ma c. Houck, or SEATTLE, wysnnwron.

11mm. om.

Application mea December 24, 192s, serial no.

To dllwhomz'tmay concern:

Be it known that I, HENRY C. Houck, a

'citizen of the United States of America, and resident of the city of Seattle, in the countyf' 5 of King and State of Washington; have invented certain new and useful Improvements in `Dental Ovens, of which the following is a specification. Y

My invention relates to an oven or furio nace which is particularly intendedv for denluse, for example in burning out inlay investments.

Such work has generally'required consid-A erable time in order to get most satisfactory i 15 results, for it has been found, if the invest'- 7ment is heated rapidly while still containing f free water, with furnaces heretofore in use,

, that it will tendto form steam throughout the investment so rapidly that, in escaping,

20 this steam will break down the investment, to such an extent as to render it unsuitable for the casting of the gold inlay. Yet it is highly desirable that some means be found for reducing the time required for burning I 2.5out such investments, for with dental laboratories and dentists making a number of such inlays, the volunie of work isJ often such rthat it would require a considerable number of furnaces to permit each invest.

0' ment ring the twelve minutes or more which -has heretofore been considered necessary for burning them out. f

My invention, therefore, has for its object the provision of a furnace in which the 35 investment may be baked morel rapidly and more perfectly than in previous furnaces,

reducing the time to four minutes or less A further object is the provision of convenient and simple means whereby the in- 4 vest-ment ringmay be perfectly centered and inserted into the furnace and conveniently handled in connection therewith.

o a A further object is the provision'of means for supporting the investment cup and forV 45 collecting the waterA andwax which run 'therefrom during the baking process, thus A to avoid the of the A Yfurtheiobject is .the rovision of a 5 simple, convenient, and `hig yl eective furnace and heating element therefor.

v My invention comprises those novelsparts and combinations thereof which are own the `'accampanyiiig drawing, described in the specification and particularly defined by the claims terminating the same.

The accompanying drawing, wherein my invention is shown in a preferred form,

Vrepresents a vertical laxial section through the furnace. i

I have found that the most satisfactory method of burning out such investments consists in the application of radiant energy to produce heat concentrated in the investment ring itself. This may most conveniently be done by inserting the investment ring into a ring formed by an electric heating e ement so that it is heated by the radiant heat therefrom upon 'all sides at once, and equally at all points.

Such a heating element may conveniently b e formed by a helical 'coil 1 of coiled resistance wire, supportedV suitably in a 12 of refractory material, for example, fire l clay. Preferably the ring is formed of two like halves, the two halves suitably connected, asl by encircling bands 11. Preferably `this ring is interiorly helically grooved, the grooves 10 receiving the resistance wirel 1, and the coils thereof lyin wholly beneath't'he inner grooved surface o the i'ing. Leads 13 from the ends of the ,resistance element 1 connect the latter Witha source of current.

Such a ring-shaped heating element is suitably supported in an elevated position A as, for example, by a stand which may consist of legs 2 and a ring 21 supported thereon, the ring 21 directly supporting the ring 12 of the heating element.. The center `of, the ring 21, beneath the vertically dispermit the passage porting an investment ring, as 4, to insert 1t into the centralv opening of rthe ring 12,. Such means may conveniently comprise a central depresion provided with supporting .flanges 51, the anges supporting the investment ring 4 and the sides of the depresion it. I have shown the anges 51 formed as part of anl adapter ring 50,A4 this porting an investment cupabove platadapter being of a shape to receive and hold the particular investment ring employed, and having an outwardly by means of which itis supported within a central opening 35 of the platform 3, or within Athe edge ofa cup 5 received therein.

'The flanges 51 are positioned, between the top of the adapter 50 and bottom of the cup 5. The adapter and the cup, it is thus seen, are both easil removable and yet are held substantially 'in' an extension of the axis of the ring 12. -Eor all practical purposes, ex cept to accommodate investment rings of varying shapes, the cup 5 and adapter -50 might be made integral. Thecup 5 'serves'f to catch the water and melted wax which run from the investment materizl and the wax model within the invstme t ring 4,

as the latter is heated. If the investment rin is not properly centered, or if it is accidentally tipped while in the furnace, no harm will result`,'as it cannot touch the wires 1, but willcontact only with the ridges betweengrooves 10.` f

Preferably means' are provided for supporting the platform3 at any elevation with..

m itsxlimitation 'of movein'ent relative to the ring 12. Such 'means are conveniently frictional. `I have shown theI platform as 1 having holes 32 about its periphery, through which the legs 2 may pass to guide the platform for vertical movement. Leaffsprings f 33 secured atone end to the platform 3 and` guided at 31 for horizontal movement,

Vmay carry slippers-30 which will' engage the`r sides of the legs 2 to frictionally support the platform 3. Two such springs 33 may be provided and these will be engageable byV the thumb and finger of airoperator `to withdraw them from engagement and to ermit vertical movement of the platform 3. yi employing an elevated adapter .50, the

- ring 4 is positionedin the most intense heat.

It will generally belfound desirable to `encase the ring 12, and to this lend I have shown an inverted cup-shaped casing 6 suitably spaced from the'v ring 12, as by set screws 61. I -have also shown a cap 15 of refractory material which is placed over the upper end of the ring .12. This may be emloyed or not as may be desired, and it may desirable at times to omit, the upper portion 62 of the casing 6, as I have found that the amou'nt of heat retainedby such covers does not, by its presence or absence, greatly affect the lactionof the furnace.

What I claim as my invention is: 1. A dentalf urnace comprising a circular heating element with itsvaxis vertically disposed, astand supporting said heating element, a platforml guided forv vertical'movement upon said stand beneath .the heating element, a cup positioned uponv but not secured to said platform, and means for supdirected shoulder form and' cup to drain into the latter.

2 KA dental furnace comprising a circular heating element with its axis vertically disposed, va stand supporting said heating element, a platform guided for vertical movement upon said stand beneath the heating element, a cup positioned upon butA not secured to said platform, and means associatied with said cup for supporting an inositioned upon but not.

vestment cup above the bottom of the lfirst A A dental furnace'comprising a circular -to support an investment cup, and means for positioning said first cup and said investment cup to enter the heating element when the platform is raised.

4. A dental furnace comprising a cireular 'heating element with its axis vertically disposed, a stand supporting said heating clefY ment, a platform guided forvertical movement upon said stand, beneath theheating element, a cup removably -supported'upoii said platform, means for supporting an investment cup above said platformand cap to drainA into the latter, and means frictionally engageable between the platformand stand to support the platform at a desired elevation. g 5. A dental furnace comprising two h frings of refractory material and means or I`securing them together to form a complete. ring, said ring being internally Y"helioally grooved2 an electric resistance element-supiorsA ported in said groove, a stand supporting said ring'with its axis vertical, a platform vertically movable upon said stand,' and means for supporting an investment' up upon said'platform and for-centering it to enter said ring. A y

6. A dental furnace comprisiigtwo halfrings of refractory material and means for securing them togeether to form a complete ring, .s aid ring'. grooved, an electric resistance element sup-y ported in said groove, a cap* of refractory material covering the top'openingofsaidl rin a casing surrounding aiidspaced from sai ring except atjits b ottom,-a standsuping 'internally 'helically porting said ring with its axis verticalra v platform vertically movable' upon said stand, and means 'for sup rting an invest--` ment ring upon said pljat erin and.I for centering it to enter said ring. v

7. A, dental voven comprisin y a platform verti 1l y fmovable beneath said l l va heating 1 u Y element having -a dWIIWI' y OPeDng' I reces and having a hole centered beneath' .said recess, a cup supported in said hole, an

adapter ring sup orted above said cup, and inwardly directe supports on said adapter to receive and support the investment ring.

8. A dental oven comprisin a heating element having a downwary opening recess adapted to receive an investment ring, vertical legs supporting said heating element, a platform guided on said legs for vertical movement towards and from the'y heating element, a pair of laterally yieldable members at opposite sides of said platform, and frictional shoes connected to said yieldable members and normally engaging the legs to support the platform therefrom, said yieldable members aiording means for engagement by a thumb and finger to release said shoes.

9. A dent-al oven comprising a heating element having a downwardly opening recess adapted to receive an investment ring, vertical legs supporting said heating element, a platform guided on said legs for vertical movement towards and from the heating element, a pair of spring leaves each connected by one end beneath opposite sides of said platform, and extending thence downwardly and outwardly, guides carried by said platform securing their outer ends for lateral movement, and a shoe connected to the outer end of each spring and normally frictionally with a leg by the outward pressure of its spring to maintain the platform at a fixed elevation.

Signed at Seattle, King County, Washington, this 17th day of December 1923.

HENRY C. HOUCK. 

